Thermodynamic/Solar Steam Generator

ABSTRACT

Disclosed is a process for generating and superheating steam.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of U.S. Prov. Pat. App. Ser. No.61/275,005 (filed Aug. 24, 2009) entitled “Thermodynamic/Solar SteamGenerator,” which document is hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

BACKGROUND OF THE INVENTION

1. Field of Invention

The present application is in the field of superheated steam generation.

2. Background of the Invention

Steam generation plus the subsequent expansion of said steam against aturbine blade is a known process for converting heat into work. Withinsaid process, steam generation has typically been accomplished viaheating water to its boiling point and until it has phase-changed tosteam. For efficiency reasons, the generated steam may be heated to ahigher temperature than the boiling point temperature (i.e.,superheated) so that heat lost during the expansion of said steamagainst a turbine blade does not result in condensation of the steam onthe turbine blade. Instead, the steam preferably attains saturation(i.e., a temperature and pressure at which the steam would condense withadditional heat loss) after its expansion against the turbine blade.Accordingly, there is a need for processes and related apparatus forheating water through a phase-change and superheating the resultantsteam.

Processes now exist for heating water through a phase-change andsuperheating the resultant steam. The heat resulting from the combustionof fossil-fuel or biomass has been effectively used to generate andsuperheat steam. However, combusting fossil-fuels or biomass has beenviewed as an inadequate heat source for producing steam due tocombustion by-products' alleged detrimental effects on the environmentand climate. The heat resulting from nuclear fission has also beeneffectively used to generate and superheat steam, but the resultingnuclear waste is extremely hazardous so that nuclear fission has not yetbeen viewed as an entirely adequate steam-generating heat source.Geothermal heat may also be used for generating and superheating steam,however, geothermal access points are not abundant and may not provideenough heat to generate a sufficient amount of steam. Finally, the heatresulting from focused solar light is yet another known means forgenerating and super heating steam, but solar light is an inadequateheat source since: (1) solar light is periodically unavailable; and, (2)methods for focusing solar radiation to produce steam, for example aconductive pipe through the focal point of a parabolic-trough mirror,evaporate flowing water within a pipe causing a two phase water/steamflow that is unstable (Ledinegg Instability) and difficult to control.Accordingly, there is a need for systems and methods of steam generationand superheating which avoid or minimize the above mentionedinadequacies of the known methods.

U.S. Pub. Pat. App. No. 2010/0154417 (published Jun. 24, 2010) disclosesvarious hybrid methods for generating and superheating steam. In oneembodiment, geothermal energy is used to generate saturated steam whilesolar radiation is focused on a conductive pipe via a parabolic-troughmirror in order to heat a working fluid (e.g., oil) for subsequentheat-exchange to superheat said saturated steam. See paragraphs [028],[029], and [021]. Although the disclosed geothermal/parabolic-troughhybrid system is said to be an advancement over non-hybrid steamgeneration, the system is not entirely preferable since an intermediateworking fluid is employed. Use of such intermediate working fluids posesrisks of hazardous spills, difficulty with VOC emissions permitting, andrequires proper handling and disposal. For this reason there is still aneed for improved systems and methods of generating and superheatingsteam.

SUMMARY OF THE INVENTION

It is an object of the present application to disclose improved systemsand methods for generating and superheating steam. A preferable systemincludes a flow of superheated steam, a flow of water, a valve formixing said flows to produce a stream of saturated steam, and means forfocusing solar radiation to superheat the stream of saturated steam. Ina suitable embodiment, the means for focusing solar radiation tosuperheat saturated steam is a conductive pipe through the focal pointof a parabolic-trough mirror or a Fresnel lens. A preferable methodincludes the steps of: mixing water with superheated steam to producesaturated steam; and, directing said saturated steam through a tube atthe focal point of a parabolic-trough mirror to superheat said saturatesteam.

It is yet another object of the present application to meet theaforementioned needs without any of the drawbacks associated withapparatus heretofore known for the same purpose. It is yet still afurther objective to meet these needs in an efficient and inexpensivemanner.

BRIEF DESCRIPTION OF THE FIGURES

The manner in which these objectives and other desirable characteristicscan be obtained is better explained in the following description andattached figures in which:

FIG. 1 diagram of a preferable system embodying this disclosure.

It is to be noted, however, that the appended figures illustrate onlytypical embodiments disclosed in this application, and therefore, arenot to be considered limiting of its scope, for the invention may admitto other equally effective embodiments that will be appreciated by thosereasonably skilled in the relevant arts. Also, figures are notnecessarily made to scale.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In general, this application discloses a preferable system includingsuperheated steam, water, a valve for mixing said water and superheatedsteam to produce a stream of saturated steam, and means for focusingsolar radiation to superheat the stream of saturated steam. A diagram ofthe preferable system is depicted in FIG. 1

Referring to FIG. 1, water (M2) at a first temperature (T2) may beintroduced into an existing superheated steam flow (M1) at a secondtemperature (T1) to produce a stream of saturated steam (M1+M2) at athird temperature (T3). The existing superheated steam (M1) may beproduced in any manner known to one of skill in the art, including butnot limited to, geothermal, solar, or the combustion of fossil fuels orbiomass. Operably, the water (M2) suitably increases in temperature tothe saturation temperature (T3) and evaporates into steam via thetransfer of thermal heat from the superheated steam (M1).Correspondingly, the temperature (T1) of the superheated steam (M1)decreases to the saturation temperature (T3) as a result of said heattransfer. Suitably, the amount of water (M2) introduced is restricted soas not to reduce steam (M1+M2) temperature (T3) to below the saturationpoint. Valves acceptable for introducing the water (M2) to thesuperheated steam (M1) will be known to those of skill in the art, butcan include those having the general design of U.S. Pat. No. 3,509,857(issued May 5, 1970). Preferably, the resultant saturated steam (M1+M2)passes through a heat conductive tube (pipe) at the focal point of amirror (including parabolic trough mirrors) so that concentrated lightor solar radiation (L) may increase the temperature of the steam (M1+M2)to a superheated temperature (T4). In an alternate embodiment, a Fresnellens (or other device that collects and concentrates thermal solarenergy) may be used to focus the solar radiation (L) onto a heatconductive pipe.

The superheated steam (M1+M2, T4) may thereafter be used for whateverpurpose including, but not limited to: (1) for expansion against aturbine blade; or (2) for the existing superheated steam flow (M1).

The following Table 1 quantitatively discloses the preferable system:

TABLE 1 Flow rate Temp Enthalpy Pressure (kg/hr) (deg. C.) (kj/kg) (bar)M1, T1 45359 395 3142 70 M2, T2 7118 115 488 80 M1 + M2, T3 52477 2872782 70 M1 + M2, T4 52477 395 3142 70

It should be noted that FIG. 1 and the associated description are ofillustrative importance only. In other words, the depiction anddescriptions of the present invention should not be construed aslimiting of the subject matter in this application. Additionalmodifications may become apparent to one skilled in the art afterreading this disclosure.

1. A system for generating and superheating steam comprising:superheated steam; water; a valve for mixing the superheated steam withthe water so that the resultant mixture is saturated steam; and, a meansfor superheating the saturated steam.
 2. The system of claim 1 whereinthe means for super heating the saturated steam is a parabolic-troughmirror and a heat transferring pipe directed through the focal pointthereof.
 3. The system of claim 1 wherein the means for super heatingthe saturated steam is a Fresnel lens and a heat transferring pipedirected through the focal point thereof.
 4. A system for generating andsuperheating steam comprising: a first flow of superheated steam; asecond flow of water; a valve for mixing said first and second flows sothat the resultant mixture is a third flow of saturated steam; and, ameans for superheating said third flow.
 5. The system of claim 4 whereinthe means for super heating the saturated steam is a parabolic-troughmirror and a heat transferring pipe directed through the focal pointthereof.
 6. The system of claim 4 wherein the means for super heatingthe saturated steam is a Fresnel lens and a heat transferring pipedirected through the focal point thereof.
 7. A method of generatingsuperheated steam from water comprising the steps of: introducing waterinto an existing flow of superheated steam so that the resultant mixtureis saturated steam; directing said resultant mixture through a heatconductive pipe; and focusing solar radiation thereon the pipe untilsaid resultant mixture is superheated.
 8. The method of claim 7 whereinsaid existing flow of superheated steam was superheated via combustingbiomass or fossil fuels.
 9. The method of claim 7 wherein said existingflow of superheated steam was superheated via the heat of nuclearfission.
 10. The method of claim 7 wherein said existing flow ofsuperheated steam was geothermally superheated.
 11. The method of claim7 wherein the step of focusing solar radiation is accomplished via atleast one parabolic-trough mirror.
 12. The method of claim 7 wherein thestep of focusing solar radiation is accomplished via at least oneFresnel lens.
 13. The method of claim 8 wherein the step of focusingsolar radiation is accomplished via at least one parabolic-troughmirror.
 14. The method of claim 8 wherein the step of focusing solarradiation is accomplished via at least one Fresnel lens.
 15. The methodof claim 9 wherein the step of focusing solar radiation is accomplishedvia at least one parabolic-trough mirror.
 16. The method of claim 9wherein the step of focusing solar radiation is accomplished via atleast one Fresnel lens.
 17. The method of claim 10 wherein the step offocusing solar radiation is accomplished via at least oneparabolic-trough mirror.
 18. The method of claim 10 wherein the step offocusing solar radiation is accomplished via at least one Fresnel lens.